Zinc-air battery systems and methods

ABSTRACT

A zinc-air battery cell assembly comprising: a cathode can that includes: a planar base, and an elongated cathode sidewall that extends to a terminal cathode sidewall end, and an anode can that includes: a planar top end, and an elongated anode sidewall that extends to a terminal anode sidewall end, the anode can disposed nested within the cathode can with the elongated anode sidewall disposed parallel and adjacent to the elongated cathode sidewall. The zinc-air battery assembly further includes a cavity defined by the cathode can and the anode can disposed nested within the cathode can, and a grommet that provides a seal between the cathode can and the anode can while also keeping the anode can and the cathode can separate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional of and claims the benefit of U.S.Provisional Application No. 63/020,655, filed May 6, 2020, entitled“ZINC-AIR BATTERY SYSTEMS AND METHODS”. This application is herebyincorporated herein by reference in its entirety and for all purposes.

This application is a non-provisional of and claims the benefit of U.S.Provisional Application No. 63/020,670, filed May 6, 2020, entitled“ZINC-AIR BATTERY COMPOSITIONS AND METHODS”. This application is herebyincorporated herein by reference in its entirety and for all purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a zinc-air battery cell assembly havingan anode and cathode can that define a cavity with anode and cathodematerials disposed within the cavity.

FIG. 2 illustrates a cross-sectional view of an example of an aircathode assembly in accordance with one embodiment, which includes afirst conductive layer, a grid disposed in a second air cathode layerand a third separator layer.

FIG. 3 illustrates a bottom perspective view of a cathode can of oneembodiment.

FIG. 4 illustrates a top internal perspective view of a cathode can ofone embodiment.

FIG. 5 illustrates an example cross-sectional view of a side portion ofa zinc-air battery cell assembly.

FIG. 6 illustrates an example method of making a zinc-air batteryassembly in accordance with an embodiment.

FIG. 7 a illustrates a method where a separator is inserted into thecavity of a cathode can.

FIG. 7 b illustrates a method where a cathode disc is inserted into thecavity of a cathode can over the separator to generate a cathode canassembly.

FIG. 8 a illustrates a method where a grommet is inserted into an anodecan.

FIG. 8 b illustrates a method where anode material is inserted into theassembly of the anode can and grommet to generate an anode can assembly.

FIG. 9 a illustrates a method where a cathode can assembly is placedinto an anode can assembly.

FIG. 9 b illustrates a method where the terminal end of the cathode iscrimped to a curved configuration such that the end of the cathodesidewall curls over the ridge and slot of the anode can to generatezinc-air battery cell assembly.

FIG. 10 a illustrates a top view of a zinc-air battery assembly of oneembodiment.

FIG. 10 b illustrates an example cross section of the embodiment of FIG.10 a.

FIG. 10 c illustrates example dimensions on one specific exampleembodiment of a zinc-air battery assembly.

FIG. 11 a illustrates a top view of a grommet in accordance with anembodiment.

FIG. 11 b illustrates a cross section of the grommet of FIG. 11 a.

FIG. 11 c illustrates a detail view of a portion of the grommet of FIG.11 b.

FIG. 12 a illustrates an example embodiment of a cathode can.

FIG. 12 b illustrates a cross-section of the embodiment of FIG. 12 a.

FIG. 13 a illustrates a close-up detail view of a portion of a cathodecan.

FIG. 13 b illustrates a close-up detail view of the cathode can of FIGS.12 a and 12 b.

FIG. 13 c illustrates a close-up detail view of the cathode can of FIGS.12 a and 12 b.

FIG. 14 a illustrates and example embodiment of an anode can.

FIG. 14 b illustrates a cross section of the example embodiment of theanode can of FIG. 14 a.

FIG. 14 c illustrates a close-up detail view of a portion of the anodecan of FIG. 14 b.

FIG. 15 a illustrates an example of air diffusion into the cavity of azinc-air battery assembly via a hole defined by a cathode can.

FIG. 15 b illustrates a perspective view of an example embodiment of acathode can.

FIG. 15 c illustrates a top view of the cathode can of FIG. 15 b.

FIG. 16 illustrates a close-up cross sectional view of a portion of azinc-air battery assembly.

FIG. 17 a illustrates a top view of an embodiment of a zinc-air batteryassembly.

FIG. 17 b illustrates an embodiment of a grommet.

FIG. 17 c illustrates an embodiment of a cathode can.

FIG. 17 d illustrates a side view of an embodiment of a zinc-air batteryassembly.

FIG. 18 a illustrates an example embodiment of an anode can

FIG. 18 b illustrates an example embodiment of a grommet.

FIG. 18 c illustrates an example embodiment of a cathode can.

It should be noted that the figures are not drawn to scale and thatelements of similar structures or functions are generally represented bylike reference numerals for illustrative purposes throughout thefigures. It also should be noted that the figures are only intended tofacilitate the description of the preferred embodiments. The figures donot illustrate every aspect of the described embodiments and do notlimit the scope of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Some zinc-air batteries can include the use of a welded woven orexpanded metal grid outside of the cathode material being connected tothe cathode can by a metal grid welded to the cathode can being pressedbetween the cathode can and the cathode disk. However, in some examples,such a method over time can have a decrease in electrical connection asthere is not a permanent and constant constraining force to keep the twomembers in contact because the cathode layer in contact with metal isexpanding and contracting during use, which can lead to separation ofthe two. An elastic and compressive conductive layer like carbonfelt/foam/pliable paper can provide a permanent and secure contactbecause this conductive layer can expand and retract with the cathode asneeded. These materials can be very conductive.

Additional zinc-air batteries can include the use of an annular ring inthe cathode can which presses into the cathode material but still makesuse of an external welded woven or expanded metal grid for electricalcontact between the cathode can and the cathode material. As with theprevious case, the electrical connection can, over time, decrease due toa loss of constraining pressure in some examples. In addition, thisembodiment can cause, in some examples, the cathode to bow away from thewire mesh grid resulting in a decreased anode cavity which provides adecreased cell capacity.

In view of the foregoing, a need exists for an improved sealing systemand method for improving the electrical connection between the cathodecan and cathode material in an effort to overcome the aforementionedobstacles and deficiencies of conventional zinc-air battery systems.

In some aspects, the present disclosure relates to a zinc-air batterycell assembly having a cathode assembly that includes the followinglayers in the following order: separator-cathode active layer-cathodeconductive layer-conductive diffusion pad. The cathode active layer cancomprise PTFE, carbon and manganese dioxide (or transitional metaloxides). A nickel mesh can be embedded in the cathode layer and in someexamples, the mesh is preferably positioned away from the separator. Thepurpose of the cathode active layer can be to enable an Oxygen ReductionReaction (ORR), which generates electrical energy. The cathode activelayer can have a mix of both hydrophobic and hydrophilic properties. Thecathode active layer can allow air diffusion and can be electricallyconductive. The cathode conductive layer, in some examples, contains notransition metal oxide and/or only contains PTFE and carbon. PTFEcontent in various embodiments can be higher in the cathode conductivelayer than the cathode active layer. In various examples, the cathodeconductive layer can be totally or substantially hydrophobic and enableselectronic conduction and air diffusion. The conductive diffusion padcan sit between a cathode can and the cathode conductive layer. In someexamples, the conductive diffusion pad can comprise carbon foam, felt orpaper. In some examples, the conductive diffusion pad can comprise anickel mesh grid, foam or expanded metal welded to the cathode can, orthe like.

In some aspects, the present disclosure relates to the achievement ofhigh-power performance and the reduction of performance variability thatcan exist in some zinc-air batteries. Various embodiments relate tohigh-power single use zinc-air batteries. “High Power” in variousembodiments and for portable applications that utilize a Zinc AirBattery can be a battery product that achieves continuous areal powercapability of equal or greater than 50 mW/cm². Various examples candefine a reaction area of a battery product as the interfacial areabetween the zinc anode and air cathode.

In one aspect, presence of a mesh in the cathode is combined with theuse of a conductive diffusion layer. The role of the mesh embedded inthe cathode can change from its traditional role of cathode conductor inthe radial plane to more that of a structural support that allows thatcathode to be made with more consistency and more cohesion.

In a further aspect, the number of holes in a zinc-air battery can beover 5 per cm² and the hole diameter can be equal or greater than 0.5mm. The holes can be arranged in a pattern so that no hole is furtherthan 5 mm from the hole closest to it or from the edge of the aircathode.

In yet another aspect, the cell can be permitted to bulge by between5-25%, which can be as a result of a high power (e.g., 50-135 mW/cm²)discharge reaction. This can allow a reduction of the void volume in acell and can promote better anode consistency, connectivity with theanode current collector and an increase in the overall anode capacity.

In various embodiments, such aspects separately and/or together, canimprove the high-power performance of primary zinc air cells. Such abattery in some examples can provide performance benefits to small(portable) rechargeable devices such as a cell phone.

Various embodiments can lead to a higher more consistent cathode runningvoltage and a zinc anode that is less susceptible to passivation andpremature failure. In some examples of a zinc air product these can beexperienced in a device as either: More power (W) capability for a givenrun time; more run time for a given power drain; or combinationsthereof.

Turning to FIG. 1 , various embodiments can include zinc-air batterycell assembly 100 that comprises a cathode can 120 made of a metallicmaterial compatible with the electrochemistry of the cell assembly 100as discussed in more detail herein. The material of the cathode can 120can comprise nickel-plated steel in some embodiments. The cathode can120 can comprise a plurality of holes 160 defined by a bottom planarbase 121 of the cathode can 120 which can allow air passage into thezinc-air battery cell assembly 100 at a calculated rate, which canproduce a redox reaction that generates an electrical circuit within thezinc-air battery cell assembly 100.

The zinc-air battery cell assembly 100 can also comprise an anode can110, which can be made of a metallic material. The anode can 110 in someexamples can comprise, consist essentially of or consist of a tri-layermaterial containing a copper layer, a steel layer and a nickel layer. Inanother embodiment, the anode can 110 can comprise, consist essentiallyof or consist of a bi-layer material having a copper layer and astainless steel layer with the copper layer being an internal surfaceand in contact with or facing an anode material 140 disposed within acavity 180 defined by the anode can 110 and cathode can 120.

A grommet 130 can surround the anode can 110 that can be made of athermoplastic material coated with styrene-butylene-styrene blockcopolymer (SBS) or styrene-butadiene copolymer (SBR) compatible with theelectrochemistry of the zinc-air battery cell assembly 100. In oneembodiment, the grommet 130 can comprise, consist essentially of orconsist of a polypropylene homo-polymer. Polyamide materials can also beused for the grommet 130 in some embodiments, and in other sealantapplications, the material of the grommet 130 can also be apolyamide-based material such as Versamid (Huntsman Advanced Materials,The Woodlands, Tex.). In various embodiments, the mechanical design of azinc-air battery cell assembly 100 can specify the style of sealant thatis desirable for ensuring appropriate compatibility with an electrolyteof the anode material 140, the gasket material and the manufacturingmethods used for application of the sealant.

The anode material 140 can be contained within the cavity 180 defined bythe anode can 110 and cathode can 120, which in some examples cancomprise, consist of, or consist essentially of zinc, aqueous potassiumhydroxide, zinc oxide and gelling agents in an aqueous slurry. While aslurry anode material 140 is desirable in some embodiments, zinc-airbattery cell assemblies 100 of some examples can be made using a pouredanode process. Even distribution of the anode material 140 within thecavity 180 can be desirable in various embodiments.

In some embodiments, if a zinc-air battery cell assembly 100 isdischarged at a low rate, high utilization may be required by thezinc-air battery cell assembly 100. In such embodiments, providing asignificant void volume in the cavity 180 of the zinc-air battery cellassembly 100 can be desirable (e.g., 30% utilized). For example, FIG. 1illustrates an example of a zinc-air battery cell assembly 100 having avoid volume 181 in the cavity 180 of the zinc-air battery cell assembly100 between the anode material 140 and a top end 111 of the anode can110. In some embodiments, current density on the anode material 140 canbe >60 mA/cm² for a high power drain, which in some examples can causethe zinc-air battery cell assembly 100 to achieve a zinc utilization of50% or less.

In some embodiments, a 15% void volume 181 can be desirable, with thevoid volume 181 being defined as the amount of space remaining in thecavity 180 of the zinc-air battery cell assembly 100 aside fromcomponents such as the anode material 140, cathode material 150, and thelike disposed within the cavity 180 in the assembled zinc-air batterycell assembly 100. In some embodiments, a desirable high-powercapability is enabled in a zinc-air battery cell assembly 100 with avoid volume 181 between 15-30% that generates a zinc utilization between30% and 80%. In further embodiments, the void volume can be 5-40%,10-35%, 20-25%, 10-20%, 5-25%, and the like.

In yet another aspect, the zinc-air battery cell assembly 100 can beconfigured to bulge, which can be as a result of expansion of the anodematerial 140 and/or cathode material 150 during a discharge reaction ofthe zinc-air battery cell assembly 100. For example, such bulging canoccur in some embodiments during a high-power discharge reaction, whichmay include a power discharge of 50-135 mW/cm², 50-100 mW/cm², 50-75mW/cm², 50-150 mW/cm², 75-135 mW/cm², 100-135 mW/cm², and the like.

Various embodiments relate to single use zinc-air battery cell assembly100, where “single use” can be defined as a zinc-air battery cellassembly 100 configured for only being discharged once without theability to re-charge the zinc-air battery cell assembly 100 after beingdischarged. For example, in various embodiments, a reaction thatgenerates power can be a one-way reaction such that the reaction cannotbe suitably reversed such that the zinc-air battery cell assembly 100can be recharged. In various embodiments, this can be distinguished froma rechargeable battery that only has a limited recharging lifespan andthe specific situation where such a battery is discharged for a finaltime and becomes inoperable.

In various embodiments, the zinc-air battery cell assembly 100 can beconfigured to bulge (e.g., increase its thickness at a maximum point) toat least between 5-25%, which in some examples can be defined as avolume displacement of the zinc-air battery cell assembly 100 from anormal configuration (e.g., as shown in FIG. 1 , where the anode andcathode cans 110, 120 are generally planar on the top and bottom of thezinc-air battery cell assembly 100). For example, bulging of thezinc-air battery cell assembly 100 can include outward bulging of thetop end 111 of the anode can 110 and/or outward bulging of the base 121.

In some examples, having the zinc-air battery cell assembly 100configured to bulge to at least a certain amount can be defined as anamount of bulge that the zinc-air battery cell assembly 100 is able tosustain without being damaged, breaking, or the like, (e.g., where sealsare broken, the anode and cathode cans 110, 120 break apart, contentswithin the zinc-air battery cell assembly 100 come out of the cavity180, etc.). In some examples, having the zinc-air battery cell assembly100 configured to bulge to at least a certain amount can be defined asan amount of bulge that the zinc-air battery cell assembly 100 is ableto sustain while still being capable of returning to an original shape,(e.g., the anode and/or cathode cans 110, 120 can deform while bulging,but can return to an original configuration when bulging is notpresent). In further embodiments, the zinc-air battery cell assembly 100can be configured to bulge an amount from 0-5%, 0-10%, 0-15%, 0-20%,0-25%, 0-30%, 0-35%, 0-40%, 0-45%, 0-50%, and the like.

In some embodiments, expansion of contents within the cavity 180 (e.g.,anode material 140 and/or cathode material 150), can result in areduction of the void volume 181 in a zinc-air battery cell assembly100, which in some examples can promote better anode consistency,connectivity with an anode current collector and an increase in overallanode capacity. Additionally, a void volume 181 in the cavity 180 can bedesirable because it can allow for expansion of the contents within thecavity 180 (e.g., anode material 140 and/or cathode material 150), whichin some examples may remove or reduce the amount of bulge that thezinc-air battery cell assembly 100 needs to accommodate. Accordingly,the volume of the void volume 181 can be configured based at least inpart on an anticipated expansion of contents within the cavity 180(e.g., anode material 140 and/or cathode material 150).

In various embodiments, a volume of anode material 140 to be present inthe cavity 180 of the zinc-air battery cell assembly 100, and thereforethe total weight of the anode material 140, can be determined initiallybased at least in part on the volume of the cavity 180 that will begenerated in an assembled zinc-air battery cell assembly 100. Such avolume of the cavity 180 can be selected based at least in part on themechanical design of the zinc-air battery cell assembly 100, andcomponents thereof, and making appropriate allowances for the separatorand its electrolyte absorption. In some specific embodiments, the anodematerial 140 can have a volume of 2.96 cc, or a volume between 3.0 and2.9 cc, 3.5-2.5 cc, and the like.

The anode material 140 can be wet (e.g., have a high weight ratio ofelectrolyte:Zinc) in various examples, and in some examples, wetter thanembodiments that run between 75-80% Zinc Weight %. Sealing canaccommodate this in some embodiments. For example, in some embodimentsthe Zinc weight % can be between 60-70%, 60-66%, 55%-75%, 58%-%72%, orthe like. Use of a zinc-air developed zinc powder from EverZinc(EverZinc Canada, Quebec, Canada) or Grillo (Grillo-Werke AG, Duisburg,Germany) is preferred in some embodiments, using zinc material used byAlkaline Button or Cylindrical Cell Company may be desirable in someexamples. A caustic electrolyte containing potassium hydroxide can beused in some embodiments (e.g., 35% KOH and 2% ZnO, or a range of33%-37%, 30-40% or 25-45% KOH and 1%-5%, 1%-4% or 1%-3% ZnO).

In some embodiments the anode material 140 can comprise a slurry orgelled composition using sodium polyacrylate of polyacrylic acid as thegellant (e.g., Carbopol 940 NF Polymer, Lubrizol Corporation, Wickliffe,Ohio). The zinc weight % in the slurry can, in some such embodiments, be64% to 74% or 62% to 74% for best results in some examples and the KOHconcentration of the electrolyte can be between 33%-37%, 30-40% or25-45%. The electrolyte of the anode material 140 may also contain zincoxide and organic inhibitors in some embodiments, such as PolyethyleneGlycol (PEG), Crown 18-6 or inorganic inhibitors such as indiumhydroxide.

Carboxymethyl cellulose (CMC) can be used as an anode expander (e.g., ina poured anode process). High molecular weight, cross-linked polyacrylicacid polymers (e.g., Carbopol) can be used as an anode expander (e.g.,in a slurry anode process). High (e.g., up to 2%) CMC content in theanode material 140 can help with cell wetness in some embodiments andthe balance between the separator and CMC absorption of electrolyte canbe tuned. In some embodiments, the type of zinc used in the anodematerial 140 can be an appropriate alloy with small amounts of zincgassing inhibitors. For example, in some embodiments, individualalloying components can be less than 500 ppm and can include Indium,Bismuth calcium, aluminum, mercury, lead, or the like.

Packing density (e.g., particle-particle contact) can be an importantvariable in various embodiments. In some examples, a large diameter(e.g., greater than 500 microns) can produce problems such that a smallcone of zinc becomes unreacted in the center of the zinc-air batterycell assembly 100. Distribution of the anode material 140 can beimportant in some embodiments, and if a poured anode material 140 isused, multiple pouring holes may be required in some examples.Alternatively, a method of manufacturing a zinc-air battery cellassembly 100 may employ a rotating fixture to ensure even filling ofanode material 140 within the cavity 180 of the zinc-air battery cellassembly 100.

It can be desirable for gassing rates of the anode material 140 to below in some embodiments (e.g., less than 0.5 cm³ after 1 week at 60°C.). In various embodiments, contaminants can be managed in some or allcomponents to current zero added mercury (Hg) zinc-air cells. Corrosioninhibitors can be dissolved in an electrolyte of the anode material 140to reduce zinc gassing. Polyethylene Glycol (PEG) can be used for thispurpose in some examples. Crown 18-6(1,4,7,10,13,16-hexaoxacyclooctadecane) can be effective for reducingzinc gassing and can be added in some examples at a level of between200-2500 ppm, 100-3500 ppm, 250-2000 ppm, 300-1500 ppm by weight ofelectrolyte, and the like. Note that as discussed herein, the terms“zinc corrosion” and “gassing,” or the like, can be synonymous invarious examples.

In various embodiments, zinc corrosion can be maintained at a low level.A corrosion rate at 60° C. of less than 0.2%/g/week or gas evolutionrate of less than 0.04 micro-liter/g/week can be desirable in someexamples. Higher corrosion/gassing rates in some embodiments can lead toleakage, cathode flooding, gas collection between the cathode andseparator, gas collection between the separator and anode and/or ionimpeding gas bubbles trapped in the zinc gel/slurry.

Various examples of aqueous alkaline batteries that have zinc anodes(e.g., anode material 140) can be configured to manage and control thecorrosion of zinc that results in the production of hydrogen gas withinthe battery. While this can be undesirable in various types ofbatteries, a zinc-air battery cell assembly 100 in various embodimentscan be particularly sensitive in some examples that have an open designand access to air. Problems that can result in some examples can includeleakage, cathode flooding, separation of components and particularlydeleterious for high power performance in some examples, the collectionof gas bubbles within the anode material 140 that can lead to impedanceand uniform zinc discharge issues.

Gassing management can be achieved in various embodiments by the use ofalloying components in the zinc of anode material 140, a focus onmaterial purity and/or by plating of an anode conductor. In addition,the use of an organic inhibitor can be added to an electrolyte of theanode material 140, and in some embodiments this can reduce the gassingreaction while at the same time not interfering with the batterydischarge reaction. Many suitable types of inhibitors can be used inembodiments of aqueous alkaline batteries including Polyethylene Glycol,Non-ionic Alkyl and/or Aryl Phosphate surfactants, for example, RA-600,Sodium dodecylbenzenesulfonate, for example, Witconate and differentPolyamines. Each of these chemicals in various examples may be able todissolve in an alkaline electrolyte, may be chemically stable in azinc-air battery cell assembly 100, may adsorb onto the zinc surface,but may not impede the electrochemical oxidation of the zinc or thedistribution of oxy-zinc products.

This disclosure in one aspect relates to a series of organic ringmolecules called, Crown Ethers that can act as complexing agents invarious embodiments and may be able, depending on their structure, totrap different cations. In one preferred embodiment, 0.2 weight percentof 18-Crown-6 is added to an alkaline electrolyte, while furtherembodiments can include 0.15-0.25 or 0.1-0.3 weight percent of18-Crown-6. Tests of an implementation having 0.2 weight percent of18-Crown-6 show that at this level, zinc corrosion of the zinc-airbattery cell assembly 100 can be reduced versus other inhibitors andthat the high-power performance is improved. 18-Crown-6 can be best forpotassium-based alkaline electrolytes in some examples, but otherCrown-style inhibitors can have efficacy and moreover can, in someexamples, be better suited for sodium or lithium hydroxide systems orelectro-chemistries that have a different anode than zinc.

The following Crown Ethers can be used in some embodiments and anelectrolyte concentration of between 0.05 weight % and 0.5 weight % canbe desirable in various examples: 18-Crown-6, 15-Crown-5, 12-Crown-4,Diaza-18-Crown-6, Di-Benzo-18 Crown-6, Diazacrowns, Cryptands,Azo-Crowns, Lariats, and the like. Some embodiments can have anelectrolyte concentration of between 0.05-0.5 weight %, 0.05-1.0 weight%, 0.05-1.5 weight %, 0.1-0.45 weight %, 0.15-0.40 weight %, 0.2-0.35weight %, 0.25-0.30 weight %, and the like.

Located between the anode material 140 and the cathode material 150 canbe a separator 190, which in some examples can act as both an electronicinsulator and an ion conductive path. In various embodiments, aseparator 190 in a zinc-air battery cell assembly 100 (e.g., ahigh-power single-use zinc-air battery) can provide electronicinsulation between the anode material 140 and the cathode material 150,but at the same time, provide for low resistance ionic conduction. Thebalancing act between the two may not be easy to achieve in variousexamples, and for a zinc-air battery cell assembly 100, in variousembodiments it can be desirable for the separator to have the addedproperty of reducing and managing the transfer of Oxygen (O₂), Watervapor (H₂O) and/or Carbon Dioxide (CO₂). This can be important for someexample applications of a zinc-air battery cell assembly 100 that canhave run times measured in days, weeks or even months as both O₂ and CO₂may pass through the separator 190 and may degrade the zinc andelectrolyte of the anode material 110 given enough time.

Separators for high power and/or low power batteries may not need lowwet ionic resistance to deliver the required level of performance andsuch separators may be characterized by small pore size to minimize gastransfer. For example, a zinc-air battery cell assembly 100 in someexamples can comprise one or more separators having pore sizes less than1 micron and wet ionic resistances of higher than 50 mohm.cm². In someembodiments, a separator can have a pore size of less than 10, 9, 8, 7,6, 5, 4, 3, 2, 1, 0.75, 0.5, 0.25 microns, or the like. In someembodiments, a separator can have wet ionic resistances of higher than100 mohm.cm², 75 mohm.cm², 50 mohm.cm², 25 mohm.cm², and the like.

In some examples of a high-power zinc-air battery cell assembly 100,such as a cell phone charger, the zinc-air battery cell assembly 100 candeliver practical energy between 1-10 hours which may be insufficienttime for deleterious gas transfer across the separator 190 to cause anunacceptable decrease in the performance of the zinc-air battery cellassembly 100. It is therefore possible, in some embodiments, for such anapplication to open up the pore size and/or increase the overallporosity of the separator 190, which can generate a benefit from areduced wet ionic resistance without causing an unacceptable decrease inthe performance of the zinc-air battery cell assembly 100 due to gastransfer across the separator 190 given expected operation time and/orone-use nature of such a zinc-air battery cell assembly 100.

An implementation of one example embodiment of a zinc-air battery cellassembly 100 a separator 190 included two layers of a PVA-Cellulosicseparator supplied by SWM (Schweitzer-Maudit International). Thismaterial had the following properties: Basis Weight: 20.5 g/m²;Thickness: 60-70 microns; Absorption: 115 g/m²; Mean Pore Size: 2.20microns; and Maximum Pore Size: 9.80 microns. When this configurationwas tested in a zinc-air battery cell assembly 100 at a rate of 70mW/cm², the example separator 190 in this example embodimentoutperformed separators 190 with smaller pore size and higher wet ionicresistance.

One preferred embodiment can include a separator 190 comprising PVAfibers blended with synthetic or natural cellulose using the dry-laid orwet-laid process. Surfactants can also be added to improve theproperties of the separator. Other separator compositions can include:Polyolefin, Polyamide, Polyester, Polysulfone and Wood Pulp.

In various embodiments, high power can be maximized for a zinc-airbattery cell assembly 100 without deleterious gas transfer across theseparator 190 when the mean pore size is between 1 and 10 microns andwhen the wet ionic resistance for the separator system (e.g., one ormore layers) is less than 50 mohm.cm². Some embodiments can have a meanpore size between 1 and 20 microns, between 1 and 15 microns, between 1and 5 microns, and the like. In some embodiments, wet ionic resistancecan be less than or equal to 100 mohm.cm², 75 mohm.cm², 50 mohm.cm², 25mohm.cm², and the like.

The cathode material 150 can be in direct contact with the cathode can120 and can be comprised of a carbon-polymer composite in some examples.In some examples, a metal oxide catalyst can be added to the cathodematerial 150 to aid an oxygen reduction reaction. Located within thearea between the planar base 121 of the cathode can 120 containing theair access holes 160 and a planar rim 122 in contact with the cathodematerial 150 can be an air diffusion member 170. This air diffusionmember 170 can be a primary means of conduction of electrical chargebetween the cathode material 150 and the cathode can 120 in variousembodiments. The air diffusion member 170 in some examples can be madeof various suitable materials such as a carbon foam, carbon felt, carbonpaper material, or the like. In some embodiments, the conductivediffusion member 170 can have a porosity of greater than 60% and anelectronic resistivity of less than 20 mohm-cm. In some embodiments, theconductive diffusion member 170 can have a porosity or open area ofgreater than 40%, 45%, 50%, 55%, 60%, 65%, 70%, the like.

While some examples can include non-woven diffusion member 170, someembodiments can comprise a diffusion member 170, a nickel mesh diffusionpad 170 (e.g., a nickel mesh diffusion pad is used instead of anon-woven diffusion pad). Such embodiments can provide desirable contactbetween the cathode material 150 and the cathode can 120 across theentire or a large portion of the surface area of the cathode material150. Some embodiments can comprise several (e.g., 4, 6, 8, 10, or thelike) spot welds or laser welds to ensure good electrical contact withthe cathode can 120. In various examples, it can be desirable for anickel diffusion pad to not interfere with air flow and/or be chemicallyreactive with composition of the zinc-air battery cell assembly 100.

In various examples, it can be desirable for the anode can 110 to notpromote excessive zinc gassing when in contact with zinc and electrolytethat may comprise the anode material 140. Accordingly, in someembodiments, it can be desirable for metal components such as the anodecan 110 and/or cathode can 120 to comprise pure copper, brass, tin orindium plating, or the like. For example, tin plating the whole of theanode can 110 can be present in some embodiments. Various examples caninclude welding to or cladding with tin plate.

One aspect of the present disclosure includes an air cathode assemblythat can comprise, consist of, or consist essentially of a multiplelayer assembly (e.g., 0.4 mm+/−0.04 mm thick), which can be circular inshape with a diameter corresponding to the size of a cathode can 120 asdiscussed herein.

FIG. 2 illustrates a cross-sectional view of an example of an aircathode assembly 200 in accordance with one embodiment, which cancomprise, consist of, or consist essentially of a first conductivecathode diffusion layer 210, a grid 220 disposed in a second active aircathode layer 230 and a third separator layer 240. In the example ofFIG. 2 , the second active air cathode layer 230 is sandwiched between,directly adjacent to and bonded to the first conductive cathodediffusion layer 210 and the third separator layer 240, without anyintervening layers.

In various examples, first conductive cathode diffusion layer 210 cancomprise, consist of, or consist essentially of a conductive microporouspolymer layer bonded to the second active air cathode layer 230. In someembodiments, the first conductive cathode diffusion layer 210 cancomprise a carbon containing polytetrafluoroethylene (PTFE). Electronicconduction in both layer 210 and layer 230 can be into and out of theplane. In some embodiments, the thickness of the conductive cathodediffusion layer 210 can be between 0.1 and 0.3 mm. In some embodimentsthe thickness of the active air cathode layer 230 can be between 0.2 and0.6 mm.

In various examples, the grid 220 can comprise, consist of, or consistessentially of a nickel mesh that may or may not be coated with carbonor graphite paint (e.g., coated with Timrex Graphite and/or Dispersions,Imerys Graphite & Carbon Switzerland SA or coated with Acheson graphitepaint, or the like). In some embodiments, the grid 220 may or may not becoated with carbon or graphite paint and fixed to the inside of acathode can 120 with a conductive glue such as MG Chemicals Super SilverEpoxy adhesive, spot welding, laser welding, or the like.

The grid 220 can be embedded into the second active air cathode layer230 and can provide stability and high-power performance consistency insome examples. In various embodiments, the grid 220 can be defined by aplurality of elongated grid elements 221 disposed in a plurality ofparallel rows and parallel columns, with the rows and columns beingperpendicular to each other and engaging at a plurality ofintersections. For example, FIG. 2 illustrates a cross-section with aplurality of grid elements 221 disposed in parallel and embedded in thesecond active air cathode layer 230. As shown in FIG. 2 , the grid 220can be planar with a plane of the grid 220 being parallel to respectiveplanes of contact between the active air cathode layer 230 and theconductive cathode diffusion layer 210 and the separator 240. In someembodiments, the grid elements 221 can comprise nickel, nickel alloys,nickel plated steel, and the like. In some embodiments, thickness ofgrid elements can be 0.05-0.25 mm. Distance between grid elements can beexpressed as % open area and can be 60% to 90% in some examples.

Additionally, as shown in the example of FIG. 2 , the grid 220 can bedisposed within the second active air cathode layer 230 proximate to theconductive cathode diffusion layer 210 or disposed closer to theconductive cathode diffusion layer 210 compared to the separator layer240. In other words, the second active air cathode layer 230 can have acentral plane and the grid 220 can be disposed within the second activeair cathode layer 230 on one side of the central plane closer to theconductive cathode diffusion layer 210. In some embodiments, the grid220 can be flush with the conductive cathode diffusion layer 210. Forexample, the grid 220 can be disposed at an external edge of the secondactive air cathode layer 230 such that the grid 220 can engage with ordirectly abut the conductive cathode diffusion layer 210

The size, position and configuration of the grid 220 illustrated in FIG.2 is provided as one example; however, in further embodiments the grid220 can have any suitable size, configuration or position relative tolayers 210 and 240. For example, in some embodiments, the grid 220 cancomprise a plurality of circular rings of various diameters with aplurality of radial grid elements extending radially from a centrallocation of the grid. Also, while an example of a grid 220 definingsquare or rectangular spaces between rows and columns of grid elements221, further embodiments can include a grid 220 including spaces of oneor more suitable shape, including triangular, pentagonal, hexagonal,heptagonal, octagonal, or the like. Additionally, grid elements 221 maynot be linear or elongated in various embodiments.

In some embodiments, the grid 220 may or may not provide an electricconduction and connection through its circumference to the cathode can120 of the zinc-air battery cell assembly 100 (see, e.g., FIG. 1 ) thatthe cathode assembly 200 is disposed in. For example, in someembodiments, one or more ends of grid elements 221 can engage thecathode can 120 of a zinc-air battery cell assembly 100 to generate anelectrical connection between the grid 220 and the cathode can 120 ofthe zinc-air battery cell assembly 100. In further examples, the grid220 can comprise a peripheral rim or other suitable element that allowsthe grid 220 to engage with and have an electrical connection with thecathode can 120 of the zinc-air battery cell assembly 100. However, itshould be clear that in various embodiments, electrical and/or physicalcontact (e.g., radially) between the grid 220 and cathode can 120 isspecifically absent.

In some embodiments an electrical connection between the active aircathode layer 230 and the cathode can 120 can be provided by aconductive carbon disk (e.g., conductive diffusion member 170). In someembodiments, such a conductive disc can comprise a felt, a foam or apaper. Such a conductive disc in some examples can have a thicknessbetween 0.1 mm and 0.25 mm and can have a resistivity of less than 20mohm.cm². Preferably, in some embodiments, the thickness of theconductive disc can be between 0.1 and 0.25 mm and the conductivity canbe between 5 and 15 mohm.cm². The conductive disk may be held in placeby pressure between the cathode assembly 200 or the cathode material 150and the cathode can 120, by adhesive, or the like.

In various embodiments, the second active air cathode layer 230 can bepressed together to form a contiguous cathode strip and can then bepressed onto a grid 220 such that the grid 220 is embedded in the secondactive air cathode layer 230. In some examples, the second active aircathode layer 230 can comprise high-conductivity carbons and/orhigh-surface-area carbons, and finely dispersed manganese dioxide allmixed together with a dispersion of polytetrafluoroethylene (PTFE) inwater. Other methods may use the permanganate method where the carbon iswashed with a permanganate solution and then dried in an oven to producethe manganese oxide catalyst.

In various embodiments, the third separator layer 240 can comprise a 25μm microporous monolayer polypropylene membrane that is laminated to apolypropylene nonwoven fabric and surfactant coated to a total thicknessof about 110 μm. For example, some embodiments of the third separatorlayer 240 can comprise Celgard 5550 (Celgard, LLC, Charlotte, N.C.). Insome examples, the separator layer 240 can be glued onto the secondactive air cathode layer 230 using various suitable adhesives such as apolyvinyl alcohol (PVA) or polyacrylic acid (PAA) based glue, or thelike. Carboxymethyl cellulose (CMC) may be included as a component ofthe separator layer 240. In some embodiments, pre-wetting of theseparator 240 can be desirable.

In various embodiments, the separator layer 240 serves to maximize ionicconduction (e.g., and minimize ionic resistance) and can provideelectronic insulation between the anode and the cathode. Ionicconduction in aqueous batteries can be enabled by separator porosity andthe presence of conducting electrolyte within the separator pores. Insome embodiments, porosity of the separator layer 240 can be between 75%and 90%. Shorting or puncture resistance can also be important in someexamples. In various embodiments, it can be important that the anode andcathode never touch; even when the cell is fresh or during dischargewhen the anode and cathode expand and the separator is squeezed betweenthem and when semi-conducting solids can deposit in the pores of theseparator layer 240. Factors that can be important in some examples canbe the separator thickness, separator tortuosity and separatormechanical integrity.

In some examples, a cathode assembly 200 can have a total thicknesses Tof between 0.3 mm and 0.7 mm, and in some embodiments preferably lessthan 0.45 mm. Further embodiments can include a cathode assembly 200having a thickness between 0.1 mm and 0.9 mm, 0.2 mm and 0.8 mm, 0.4 mmand 0.6 mm, 0.5 mm and 0.2 mm, 0.5 mm and 0.3 mm, 0.5 mm and 0.4 mm, orthe like.

In some examples, such an air cathode assembly 200 embodied in azinc-air battery cell assembly 100 (or other embodiments of a zinc-airbattery cell assembly 100 discussed herein) can have a minimumcontinuous power capability of 60 mW/cm², 70 mW/cm², 80 mW/cm², 90mW/cm², 100 mW/cm², 110 mW/cm², 120 mW/cm², 130 mW/cm², 135 mW/cm² 140mW/cm², 150 mW/cm², and the like.

It should be noted that the examples of FIGS. 1 and 2 can be suitablycombined in various ways and that the elements of one given exampleshould not be considered to be exclusive to that illustrativeembodiment. For example, in on embodiment, the cathode material 150 ofFIG. 1 can comprise, consist of or consist essentially of an active aircathode layer 230 and the conductive cathode diffusion layer 210 of FIG.2 . Accordingly, various suitable elements of FIGS. 1 and 2 should beconsidered interchangeable, or may be specifically absent in someembodiments. For example, the cathode material 150 of FIG. 1 can beinterchangeable with the combined active air cathode layer 230 andconductive cathode diffusion layer 210 of FIG. 2 . In another example,the third separator layer 240 of FIG. 2 can be interchangeable with theseparator 190 of FIG. 1 . In a further example the cathode assembly 200of FIG. 2 (having an air cathode layer 230, conductive cathode diffusionlayer 210 and separator layer 240), can be interchangeable with thecathode material 150 and separator 190 of FIG. 1 .

Turning to FIGS. 3-5 , various embodiments can make use of a series ofprotrusions 310 formed into the planar rim 122 of the cathode can 120that can be in contact with the cathode material 150 such as shown inFIG. 5 . As shown in the example of FIGS. 3 and 4 , these protrusions310 can be formed in a circular pattern about the central axis of thecathode can 120 with the protrusions 310 located on the planar rim 122and extending into the cavity 180 of the cathode can 120. For example,in some embodiments, the protrusions 310 can be formed in a cathode can120 by stamping the protrusions into the planar rim 122 such that theprotrusions 310 extend into the cavity 180 of the cathode can 120 asshown in FIG. 4 , and leave a protrusion slot on the external side ofthe planar rim 122 of the cathode can 120 as shown in FIG. 3 .

The size, shape and count of these protrusions 310 are not restricted bythe present disclosure and the specific example embodiments shown anddescribed should not be construed to be limiting. In some examples, suchas shown in FIGS. 3 and 4 , the cathode can 120 can comprise 18protrusions 310 with a protrusion height between 0.05-0.15 mm and aprotrusion width between 0.5 and 1.50 mm and a length between 3.0 and5.0 mm, having a generally rectangular cross-section and stepping up toa maximum protrusion height from opposing ends of the protrusion. Insome embodiments, protrusions 310 can be spaced apart by 1.5 mm +/−0.2mm).

Further embodiments can have a protrusion height from the face of theplanar rim 122 of 0.05-0.25, 0.05-0.20, 0.05-0.15, 0.05-0.10, 0.10-0.15mm and the like. Some embodiments can have a protrusion width between0.5 and 2.00 mm, 0.5 and 1.50 mm, 0.5 and 1.00 mm, 1.0 and 1.50 mm, andthe like. Some embodiments can have a protrusion length between 1.0 and7.0 mm, 2.0 and 6.0 mm, 3.0 and 5.0 mm, 4.0 and 6.0 mm, 2.0 and 4.0 mm,and the like. Protrusions 310 can be spaced apart by 1.4-1.6 mm, 1.3-1.7mm, 1.2-1.8 mm, 1.1-1.9 mm, 1-2 mm, and the like. Various embodimentscan include any suitable number of protrusions, including 2, 4, 6, 8,10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 45, 50,75, 100, 125, 150, 200, and the like. Also, while the examples of FIGS.3 and 4 illustrate protrusions 310 that are the same size and shape andspaced apart the same amount, further embodiments can includingprotrusions 310 that are different shapes and/or sizes, which may or maynot be spaced apart different amounts.

The dimensions and configuration of protrusions 310 in furtherembodiments can be based upon the size, shape and configuration of thezinc-air battery cell assembly 100. In various embodiments, upon closureof the zinc-air battery cell assembly 100 as discussed herein, theprotrusions 310 penetrate the cathode material 150 and make contact witha metal screen mesh (e.g., grid 220) embedded inside the cathodematerial 150, which can generate a permanent and secure contact betweenthe metal screen mesh and the cathode can 120. The penetration of theprotrusions 310 into the cathode material 150 can, in various examples,place the cathode material 150 under increased compression, which canprovide for better sealing between the cathode can 120 and cathodematerial 150. In some embodiments, a portion of the cathode material 150compressed by the protrusions 310 flows into the areas 315 between theprotrusions 310, which can increase the volumetric amount of cathodematerial 150 in those areas 315 which can increase the pressure on thecathode material 150 to an amount similar to the pressure on the cathodematerial 150 in areas of the cathode material 150 compressed byprotrusions 310. Another aspect of the protrusions 310 can be to putincreased pressure on the cathode material 150 which can provide forbetter sealing between a grommet 130 (see FIGS. 1 and 5 ) and thecathode material 150.

As shown in FIG. 5 , anode can 110 can comprise a planar top end 111(see FIG. 1 ) that peripherally curves downward to define a slot 112with a ridge 113, that extends to an elongated anode sidewall 114, whichextends perpendicular to the planar top end 111 of the anode can 110.The cathode can 120 can comprise an elongated cathode sidewall 123 thatextends perpendicular to the planar base 121 and planar rim 122 of thecathode can 120. The anode can 110 can be configured to be disposedwithin the cathode can 120 with the anode and cathode sidewalls 114, 123being disposed in parallel and adjacent as shown in the example of FIG.5 .

In various embodiments, the zinc-air battery cell assembly 100 cancomprise a grommet 130 that provides a seal between the anode can 110and the cathode can 120 while also keeping the anode can 110 and cathodecan 120 physically and electrically separate. For example, as shown inthe example of FIG. 5 , the grommet 130 can surround an end 115 of theanode sidewall 114 with a first elongated portion 131 of the grommet 130being disposed between the anode and cathode sidewalls 114, 123. The end115 of the anode sidewall 114 can be disposed within a grommet slot 132,with a second elongated portion 133 of the grommet 130 extending alongan internal portion of the anode sidewall 114 with the first and secondelongated portions 131, 133 being coupled via bridge portion 136 thatdefines a portion of the grommet slot 132.

An end 134 of the first elongated portion 131 can be configured toextend over the ridge 113 and into the slot 112 of the anode can 110.For example, as discussed in more detail herein, an end 124 of thecathode sidewall 123 can be crimped to the configuration shown in FIG. 5, where the end 124 of the cathode sidewall 123 curls over the ridge 113and slot 112 (compared to the configuration of the end 124 of thecathode sidewall 123 shown in FIG. 4 ). As discussed in more detailherein, such crimping of the end 124 of the cathode sidewall 123 cancreate a seal between the anode can 110 and cathode can 120 via thegrommet 130.

In various embodiments, the grommet 130 can further comprise feet 135A,135B, that can compress against the cathode material 150 and/orseparator 190, which can provide increased leakage protection for thezinc-air battery cell assembly 100. For example, the feet 135A, 135B canprovide an improved seal between the anode can 110 and cathode can 120such that contents within the cavity 180 of the zinc-air battery cellassembly 100 such as the anode material 140 and/or cathode material 150is prevented from leaking out from between the anode can 110 and cathodecan 120, even where anode material 140 and/or cathode material 150expands within the cavity 180 as discussed herein.

As shown in the example of FIG. 5 , a first foot 135A can be present ata peripheral edge of the bridge portion 136 of the grommet 130 proximateto the second elongated portion 133 and the second foot 135B can bepresent on an opposing peripheral edge of the bridge portion 136proximate to the first elongated portion 131. The feet 135A, 135B can bevarious suitable sizes and shapes. For example, in some embodiments, thefeet 135A, 135B can be generally the same width as the first and secondelongated portions 131, 133 and spaced apart the thickness of the anodesidewall 114.

In various embodiments, compression of the grommet 130 and the feet135A, 135B into the cathode material 150 and/or separator 190 can begenerated by the application of a downward force of the anode can 110into the grommet 130, which in some examples can be caused by a closureprocess of the zinc-air battery cell assembly 100 such as crimping ofthe end 124 of the cathode sidewall 123 to create a seal between theanode can 110 and cathode can 120 via the grommet 130 as discussedherein.

The feet 135A, 135B can provide an increased compressive force betweenthe grommet 130 and the cathode material 150 and/or separator 190. Afirst area of higher compression generated by the first foot 135A can,for example, act as a dam blocking the movement of electrolyte from theanode material 140 area across the interface between the cathodematerial 150 and/or separator 190 and grommet 130. The area of thebridge portion 136 between the feet 135A, 135B can be under compression,which can provide an additional tortuous path blocking the flow ofelectrolyte from the anode material 140 area across the interfacebetween the cathode material 150 and/or separator 190 and grommet 130. Asecond area of higher compression generated by the second foot 135B canact as a sealing surface, which can further block the movement of anyelectrolyte from the anode material 140 across the interface between thecathode material 150 and/or separator 190 and grommet 130. The use oftwo or more higher-pressure areas can ensure that electrolyte containedwithin the cavity 180 is not allowed to leak from the zinc air batterycell assembly 100. Accordingly, the novel configuration of the feet135A, 135B of the grommet 130 in various embodiments cannot beconsidered a mere design choice given the improved sealing that can begenerated by specific configurations of the feet 135A, 135B.

In some embodiments, a crimped zinc-air battery assembly 100 cantolerate at least 50 psi internal pressure (e.g., generated by expansionof the anode material 140 and/or cathode material 150) without openingof a crimping of the end 124 of the cathode sidewall 123 that creates aseal between the anode can 110 and cathode can 120 via the grommet 130and/or pressure that will force the force electrolyte into the cathodeand cause failure of the zinc-air battery assembly 100. Furtherembodiments can be configured to tolerate at least 10 psi, 20 psi, 30psi, 40 psi, 50 psi, 60 psi, 70 psi, 80 psi, 90 psi, 100 psi, 110 psi,120 psi, 130 psi, 140 psi, 150 psi, and the like. Various examples of azinc-air battery assembly 100 do not have any pressure build up undernormal temperature of use and storage up to 45° C. because, in someembodiments, hydrogen can permeate through the cathode material 150easily. In some embodiments, a zinc-air battery assembly 100 does nothave any pressure build up under normal temperature of use and storageup to 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C.,70° C., and the like.

For many applications, the zinc-air battery assembly 100 of variousembodiments offers the longest run time of any primary aqueous batterysystem with flat discharge voltage, safety and low cost. However, whenin use in various examples, a zinc-air battery assembly 100 can be opento the ambient atmosphere; therefore, the zinc-air battery assembly 100may not be independent of environmental conditions. Drying out in lowhumidity conditions in some examples can limit life once opened to theair.

Flooding of a zinc-air battery assembly 100 in a high humidityenvironment can limit power output and activated life of the zinc-airbattery assembly 100 in some examples. Air access management cantherefore be an important feature for zinc-air battery assemblies 100 insome embodiments. Therefore, air holes 160 in some examples can bedesigned to meet a minimum 50 mW/cm² discharge and activated liferequirement of 24 hours. For example, in one embodiment, the number ofholes 160 defined by the cathode can 120 of a zinc-air battery assembly100 can be over 5 per cm² and the hole diameter can be equal or greaterthan 0.5 mm and the holes 160 can be arranged in a pattern so that nohole 160 is further than 5 mm from the hole 160 closest to it or fromthe edge of the air cathode.

In some embodiments, the number of holes 160 defined by the cathode can120 of a zinc-air battery assembly 100 can be over 1 per cm², 2 per cm²,3 per cm², 4 per cm², 5 per cm², 6 per cm², 7 per cm², 8 per cm², 9 percm², 10 per cm², 15 per cm², 20 per cm², and the like. In someembodiments, hole diameter can be greater than 0.1 mm, 0.2 mm, 0.3 mm,0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, and the like. Insome embodiments, hole diameter can be between 0.1 mm and 1.0 mm, 0.2 mmand 0.9 mm, 0.3 mm and 0.8 mm, 0.4 mm and 0.7 mm, 0.5 mm and 0.6 mm, andthe like. In some embodiments, holes 160 can be arranged in a pattern sothat no hole 160 is further than, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7mm, 8 mm, 9 mm, 10 mm, or the like, from the hole 160 closest to itand/or from the edge of the air cathode can 120.

Regulation can be desirable in various embodiments because other gases,like hydrogen, water vapor and carbon dioxide can enter or leave thecavity 180 of the zinc-air battery assembly 100. If not properlycontrolled, in some examples, undesirable gas transfer can causeperformance degradation including degradation of service life of thezinc-air battery assembly 100. Water vapor transfer can be the dominantform of gas transfer that can result in performance degradation in someexamples. This transfer of water vapor can occur in various exampleswhen electrolyte and the ambient relative humidity are not equal.

In some embodiments, the electrolyte of a zinc-air battery assembly 100can be in equilibrium with the ambient room temperature when relativehumidity is approximately 55%. Accordingly, in some conditions such azinc-air battery assembly 100 can lose water on drier days and gainwater on more humid days. In some examples, water gain or water loss cancause the zinc-air battery assembly 100 to fail before delivering theintended performance. Smaller and more evenly distributed holes 160 inthe zinc-air battery assembly 100 can slow down the exchange in someexamples. Another measure to increase tolerance can be making sure thatthe tortuous path in the cathode diffusion layer is adequate.

In some examples, a zinc anode material 140 can be a porous structure ofgranulated powder in mix with electrolyte and a gelling agent. Metalcathode and anode cans 110, 120 for housing cathode and anode activematerials 140, 150 can also act as the terminals with a plastic gasket(e.g., grommet 130) in between to insulate.

In various embodiments, a portion of the total volume of the cavity 180of a zinc-air battery assembly 100 can be a void volume 181 reserved toaccommodate the expansion that occurs when zinc is converted to zincoxide during power discharge of the zinc-air battery assembly 100. Thisvoid volume 181, (e.g., 15% to 25% of the total volume of the cavity180), can provide additional tolerance to sustained water gain duringhigh humidity operating conditions. For example, some embodiments caninclude an initial void volume 181 within the available volume of thecavity 180 of 15%, 18%, 21%, 23%, 25%, or the like, to accommodate this.In further embodiments, the void volume 181 can be 14-16%, 17-19%,20-22%, 22-24%, 24-26%, 5-40%, 10-35%, 20-25%, 10-20%, 5-25%, and thelike. In some embodiments, the void volume 181 can be 0.5-5.5 cc,1.0-5.0 cc, 1.5-4.5 cc, 2.0-4.0 cc, 2.5-3.5 cc, 2.0-3.0 cc, and thelike.

In some embodiments, mechanisms that degrade a zinc-air battery assembly100 during storage and use can be (1) corrosion of the zinc withhydrogen gas evolution and/or (2) gas transfer. Gas transfer can includedirect oxidation of the zinc anode material 140, carbonation of anelectrolyte, and electrolyte water gain or loss. During storage, airaccess holes 160 of the cell can be sealed to minimize degradation bygas transfer. Adhesive tape containing a polyester layer can be used insome examples to cover the vent holes 160 when the zinc-air batteryassembly 100 is not in use.

A zinc-air battery assembly 100 and components thereof can be configuredin any suitable way. For example, FIGS. 10 a -18 illustrate exampleembodiments of a zinc-air battery assembly 100 and/or componentsthereof. For example, FIG. 10 a illustrates a top view of a zinc-airbattery assembly 100 of one embodiment, FIG. 10 b illustrates an examplecross section of the embodiment of FIG. 10 a , and FIG. 10 c illustratesexample dimensions on one specific example embodiment of a zinc-airbattery assembly 100 in millimeters. FIG. 11 a illustrates a top view ofa grommet 130 in accordance with an embodiment, FIG. 11 b illustrates across section of the example embodiment of FIG. 11 a with exampledimensions in millimeters, and FIG. 11 c illustrates a detail view of aportion of FIG. 11 b.

FIG. 12 a illustrates an example embodiment of a cathode can 120 andFIG. 12 b illustrates a cross-section of the embodiment of FIG. 12 awith example dimensions in millimeters. FIG. 13 a illustrates a close-updetail view of a portion of a cathode can 120, FIG. 13 b illustrates aclose-up detail view of the cathode can 120 of FIGS. 12 a and 12 b withexample dimensions in millimeters, and FIG. 13 c illustrates a close-updetail view of the cathode can 120 of FIGS. 12 a and 12 b with exampledimensions in millimeters.

FIG. 14 a illustrates an example embodiment of an anode can 110, FIG. 14b illustrates a cross section of the example embodiment of the anode can110 of FIG. 14 a with example dimensions in millimeters, and FIG. 14 cillustrates a close-up detail view of a portion of FIG. 14 b withexample dimensions in millimeters. FIG. 15 a illustrates an example ofair diffusion into the cavity 180 of a zinc-air battery assembly 100 viaa hole 160 defined by a cathode can 120, FIG. 15 b illustrates aperspective view of an example embodiment of a cathode can 120 and FIG.15 c illustrates a top view of the cathode can 120 of FIG. 15 b.

FIG. 16 illustrates a close-up cross sectional view of a portion of azinc-air battery assembly 100 with example and non-limiting dimensionsin millimeters. FIG. 17 a illustrates a top view of an embodiment of azinc-air battery assembly 100, FIG. 17 b illustrates an embodiment of agrommet 130, FIG. 17 c illustrates an embodiment of a cathode can 120,and FIG. 17 d illustrates a side view of an embodiment of a zinc-airbattery assembly 100 with example dimensions in millimeters. FIG. 18 aillustrates an example embodiment of an anode can 110, FIG. 18 billustrates an example embodiment of a grommet 130, and FIG. 18 cillustrates an example embodiment of a cathode can 120, with exampledimensions in millimeters.

FIG. 6 illustrates an example method 600 of making a zinc-air batteryassembly 100 in accordance with an embodiment. The method 600 begins at605 where a diffusion pad (e.g., diffusion member 170) is inserted intothe cavity 180 of a cathode can 120 (see, e.g., FIG. 7 a ), and at 610,a cathode disc (e.g., cathode material 150, cathode assembly 200, or thelike) is inserted into the cavity 180 of a cathode can 120 over theseparator to generate a cathode can assembly (see, e.g., FIG. 7 b ).

At 620, a separator (e.g., separator 190) is inserted into the cavity180 of the cathode can 120 over the cathode disc. However, note that insome embodiments, the cathode disc can comprise a separator, so the stepof 620 can be absent and a separator (e.g., separator 190 or 240) can beintroduced via the cathode disc. Similarly, in some embodiments, thecathode disc can include a diffusion pad, so the step 605 can be absentand the diffusion pad (e.g., diffusion member 170, 210) can beintroduced via the cathode disc.

At 630, a grommet 130 is inserted into an anode can 110 (see, e.g., FIG.8 a ) and at 640, anode material 140 is inserted into the assembly ofthe anode can 110 and grommet 130 assembled at 630 to generate an anodecan assembly (see e.g., FIG. 8 b ). At 650, the cathode can assemblygenerated at 620 is placed into the anode can assembly generated at 640,and at 660, the assembly generated at 650 is crimped to generate azinc-air battery assembly 100. For example, the terminal end 124 of thecathode can sidewall 123 can initially be in a straight configuration asshown in FIGS. 4 and 9 a and can be crimped to a curved configuration asshown in FIG. 5 or 9 b such that the end 124 of the cathode sidewall 123curls over the ridge 113 and slot 112 of the anode can 110, which cancreate a seal between the anode can 110 and cathode can 120 via thegrommet 130 as discussed herein.

In some embodiments, a cathode assembly 200, including the separatorlayer 240 can be shipped to a button cell manufacturer to generate azinc-air battery cell assembly 100 having the air cathode assembly 200and an anode material 140 disposed in the cavity 180 defined by anodecan 110 and cathode can 120 as discussed herein.

The described embodiments are susceptible to various modifications andalternative forms, and specific examples thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the described embodiments are not to belimited to the particular forms or methods disclosed, but to thecontrary, the present disclosure is to cover all modifications,equivalents, and alternatives. Additionally, elements of a givenembodiment should not be construed to be applicable to only that exampleembodiment and therefore elements of one example embodiment can beapplicable to other embodiments. Additionally, elements that arespecifically shown in example embodiments should be construed to coverembodiments that comprise, consist essentially of, or consist of suchelements, or such elements can be explicitly absent from furtherembodiments. Accordingly, the recitation of an element being present inone example should be construed to support some embodiments where suchan element is explicitly absent.

What is claimed is:
 1. A zinc-air battery cell assembly comprising: acircular metal cathode can that includes a planar base that extends to,at a periphery of the planar base, a planar rim that is parallel to theplanar base, the planar rim extending to an elongated cathode sidewallthat extends perpendicular to a plane of the planar base, the elongatedcathode sidewall extending to a terminal cathode sidewall end, theplanar base defining a plurality of air holes that extend through theplanar base; a circular metal anode can that includes a planar top endthat extends to, at a periphery of the planar top end, a slot with aridge, with the ridge extending to an elongated anode sidewall thatextends perpendicular to a plane of the planar top end, the elongatedanode sidewall extending to a terminal anode sidewall end, the circularmetal anode can disposed nested within the circular metal cathode canwith the elongated anode sidewall disposed parallel and adjacent to theelongated cathode sidewall; a cavity defined by the circular metalcathode can and the circular metal anode disposed nested within thecircular metal cathode can, the cavity including: a layer of anodematerial, a layer of cathode material, and a void volume, between theanode material and the planar top end of the circular metal anode can,that is between 15% to 25% of a total volume of the cavity defined bythe circular metal cathode can and the circular metal anode; and agrommet that provides a seal between the circular metal cathode can andthe circular metal anode while also keeping the circular metal anode canand cathode can physically and electrically separate, the grommetcomprising: a first elongated grommet portion disposed between andengaging the parallel anode and cathode sidewalls, a second elongatedgrommet portion extending along an internal portion of the elongatedanode sidewall and proximate to the anode material and cathode material,a grommet slot defined by a grommet bridge portion that couples thefirst and second elongated grommet portions, with the terminal anodesidewall end disposed within the grommet slot, the grommet bridgedisposed over the planar rim of the circular metal cathode can, a firstand second foot that extend from the grommet bridge portion and engagewith the layer of cathode material in the cavity over the planar rim ofthe circular metal cathode can, first foot disposed at a firstperipheral edge of the grommet bridge portion proximate to the secondelongated portion, and the second foot disposed on an opposing secondperipheral edge of the bridge portion proximate to the first elongatedportion, wherein the terminal cathode sidewall end of the cathodesidewall is crimped to a curved configuration such that the terminalcathode sidewall end of the cathode sidewall and an end of the firstelongated grommet portion both curve over the ridge and slot of thecircular metal anode can and generates a seal between the circular metalanode can and circular metal cathode can via the grommet.
 2. Thezinc-air battery cell assembly of claim 1, wherein the first foot andsecond foot of the grommet generate a compressive force between thegrommet and the layer of cathode material in the cavity, including: afirst area of compression generated by the first foot that acts as a damblocking movement of a liquid of the layer of anode material across aninterface between the layer of cathode material and the grommet, and asecond area of compression generated by the second foot that acts as asealing surface blocking movement of the liquid of the layer of anodematerial across the interface between the layer of cathode material andthe grommet.
 3. The zinc-air battery cell assembly of claim 1, whereinthe zinc-air battery cell assembly is configured to bulge in volume bybetween 5-25%, as a result of expansion of at least one of the layer ofanode material and the layer of cathode material during a dischargereaction of the zinc-air battery cell assembly, zinc-air battery cellassembly configured to bulge in volume by between 5-25% without damagingor breaking the seal between the circular metal anode can and circularmetal cathode can via the grommet and without breaking the circularmetal anode can and circular metal cathode can.
 4. The zinc-air batterycell assembly of claim 1, wherein the zinc-air battery cell assembly isa single use zinc-air battery cell assembly such that the zinc-airbattery cell assembly is configured for only being discharged oncewithout the ability to re-charge the zinc-air battery cell assemblyafter being discharged.
 5. The zinc-air battery cell assembly of claim1, wherein the plurality of air holes are defined by the planar base ofthe circular metal cathode can at a density of over 5 air holes per cm²of the planar base, with an air hole diameter of the respective airholes greater than 0.5 mm, wherein the plurality of air holes arearranged in a pattern such that no air hole is further than 5 mm from aclosest air hole or from a peripheral edge of the planar base.
 6. Azinc-air battery cell assembly comprising: a metal cathode can thatincludes: a planar base, an elongated cathode sidewall that extendsperpendicular to a plane of the planar base, the elongated cathodesidewall extending to a terminal cathode sidewall end, and a pluralityof air holes defined by the planar base; a metal anode can thatincludes: a planar top end, an elongated anode sidewall that extendsperpendicular to a plane of the planar top end, the elongated anodesidewall extending to a terminal anode sidewall end, the metal anode candisposed nested within the metal cathode can with the elongated anodesidewall disposed parallel and adjacent to the elongated cathodesidewall; a cavity defined by the metal cathode can and the metal anodedisposed nested within the metal cathode can, the cavity including: alayer of anode material, a layer of cathode material, and a void volume,wherein the void volume is between 15% to 25% of a total volume of thecavity defined by the metal cathode can and the metal anode; and agrommet that provides a seal between the metal cathode can and the metalanode while also keeping the metal anode can and cathode can physicallyand electrically separate.
 7. The zinc-air battery cell assembly ofclaim 6, wherein the planar top end of the metal anode can extends to,at a periphery of the planar top end, a slot with a ridge.
 8. Thezinc-air battery cell assembly of claim 6, wherein the grommetcomprises: a first elongated grommet portion disposed between andengaging the parallel anode and cathode sidewalls, a second elongatedgrommet portion extending along an internal portion of the elongatedanode sidewall, a grommet slot defined by a grommet bridge portion thatcouples the first and second elongated grommet portions, with theterminal anode sidewall end disposed within the grommet slot, and afirst and second foot that extend from the grommet bridge portion andengage with the layer of cathode material in the cavity, first footdisposed at a first peripheral edge of the grommet bridge portionproximate to the second elongated portion, and the second foot disposedon an opposing second peripheral edge of the bridge portion proximate tothe first elongated portion.
 9. The zinc-air battery cell assembly ofclaim 6, wherein the terminal cathode sidewall end of the cathodesidewall is crimped to a curved configuration such that the terminalcathode sidewall end of the cathode sidewall curves over the metal anodecan and generates a seal between the metal anode can and the metalcathode can via the grommet.
 10. The zinc-air battery cell assembly ofclaim 6, wherein the zinc-air battery cell assembly is configured tobulge in volume by between 5-25%, as a result of expansion of at leastone of the layer of anode material and the layer of cathode materialduring a discharge reaction of the zinc-air battery cell assembly,zinc-air battery cell assembly configured to bulge in volume by between5-25% without damaging or breaking the seal between the metal anode canand metal cathode can via the grommet and without breaking the metalanode can and metal cathode can.
 11. The zinc-air battery cell assemblyof claim 6, wherein the zinc-air battery cell assembly is a single usezinc-air battery cell assembly such that the zinc-air battery cellassembly is configured for only being discharged once without theability to re-charge the zinc-air battery cell assembly after beingdischarged.
 12. The zinc-air battery cell assembly of claim 6, whereinthe plurality of air holes are defined by the planar base of the metalcathode can at a density of over 5 air holes per cm² of the planar base,with an air hole diameter of the respective air holes greater than 0.5mm, wherein the plurality of air holes are arranged in a pattern suchthat no air hole is further than 5 mm from a closest air hole or from aperipheral edge of the planar base.
 13. A zinc-air battery cell assemblycomprising: a cathode can that includes: a planar base, and an elongatedcathode sidewall that extends to a terminal cathode sidewall end, and ananode can that includes: a planar top end, and an elongated anodesidewall that extends to a terminal anode sidewall end, the anode candisposed nested within the cathode can with the elongated anode sidewalldisposed parallel and adjacent to the elongated cathode sidewall; acavity defined by the cathode can and the anode can disposed nestedwithin the cathode can comprises: an anode material, a cathode material,and a void volume, wherein the void volume is between 15% to 25% of atotal volume of the cavity defined by the cathode can and the anode can,and a grommet that provides a seal between the cathode can and the anodecan while also keeping the anode can and the cathode can separate. 14.The zinc-air battery cell assembly of claim 13, wherein the elongatedcathode sidewall extends perpendicular to a plane of the planar base andwherein the elongated anode sidewall extends perpendicular to a plane ofthe planar top end.
 15. The zinc-air battery cell assembly of claim 13,wherein the terminal cathode sidewall end of the cathode sidewall iscrimped to a curved configuration such that the terminal cathodesidewall end of the cathode sidewall curves over the anode can andgenerates a seal between the anode can and the cathode can via thegrommet.
 16. The zinc-air battery cell assembly of claim 13, wherein thezinc-air battery cell assembly is configured to bulge in volume bybetween 5-25%, as a result of expansion of material in the cavity duringa discharge reaction of the zinc-air battery cell assembly, zinc-airbattery cell assembly configured to bulge in volume by between 5-25%without damaging or breaking a seal between the anode can and cathodecan via the grommet and without breaking the anode can and cathode can.17. The zinc-air battery cell assembly of claim 13, wherein the cathodecan further comprises a planar base that defines a plurality of airholes at a density of over 5 air holes per cm² of the planar base, withan air hole diameter of the respective air holes greater than 0.5 mm,wherein the plurality of air holes are arranged in a pattern such thatno air hole is further than 5 mm from a closest air hole or from aperipheral edge of the planar base.